Illuminating Reality

The average sci-fi fan likely takes for granted the speed of light and no doubt breaking the speed limit so callously is an expected aspect of story telling, but there are some really interesting implications to traveling at relativistic speed that I don’t think a whole lot of people are aware of. A fairly simple implication is, from our point of view, that an object approaching us at or near the speed of light (ie relativistic speed) appears as tinted blue. A more complicated implication is that time is running slower for the relativistic passenger. Let me explain…

Let’s say there’s a guy riding a motorcycle near the speed of light.  Because light acts like a wave, the motion of the object is going to compress and stretch the light waves radiating from it.  This is known as the Doppler Effect and is evident every time you pass a blaring siren – you hear the pitch rise as you approach it and then drop off as you move away from it – “yyyyyeeeeaaaarrrrooooowww!”  This is simply because the sound waves are being compressed as you approach it; this shortens the wavelength and creates a higher frequency sound.  Naturally, as it recedes, the sound drops in pitch because the waves are stretched to lower frequencies.

This is really a property of all waves, including light.  In fact, it’s happening all around us but the amount of shift in the light spectrum is so tiny that we just can’t detect it.  However taking our scenario above, the speed of the motorcycle rider would significantly amplify the shift and he would appear to turn blue as he approached you and red as he passed you.  Incidentally, this Doppler Shift is used by astronomers to detect planets orbiting other stars (among other things).

Another interesting implication of traveling at relativistic speed is that time slows down for the traveler in relation to the observer.  This is known as Time Dilation and is a result of time being relative from observer to observer as described by Einstein’s Theory of Relativity.  In the case of our motorcycle rider, because of his speed his watch appears to run slower to the people observing him.  This is a strange property of the Universe but we observe it in many places.  One of the best examples is muon decay from cosmic rays colliding with our upper atmosphere.

Cosmic Rays are high energy particles formed in powerful celestial events such as the cores of stars, supernovae, neutron stars and black holes.  They blast out in every direction in the cosmos and daily they smack into our atmosphere.*  When these protons collide with air molecules they break apart into sub-atomic particles that decay very quickly.  One of these types of sub-atomic particles is the Muon, something very similar to the Electron yet significantly more massive and highly unstable.  Muons created in these collisions live for one to two microseconds or 1.0 × 10^-6 seconds.  That’s a ridiculously short time so it would be expected that we can only detect these muons in the upper atmosphere because there aren’t around long enough to make it to the surface – even traveling at the speed of light.  Yet they reach muon detectors on the surface daily!  What gives?

The reason is because of Time Dilation, pure and simple.  The one to two microseconds the muon experience appear to be longer to us, the observer.  In other words, time for the muon runs slower from our point of view.  To explain why is a bit involved, but the video below does a good job.  In a nutshell, relativity is allows for time to be flexible to keep the speed of light a constant for everyone.

* it should be noted that these collisions are at MUCH higher energies than that produced by the LHC, and because the Earth is still here it’s safe to assume that the LHC can’t produce an Earth devouring black hole – otherwise it would have already happened.

Have you heard that the Universe is expanding? Edwin Hubble changed astronomy in the 1920s by discovering this, but did you also know that the expansion of the Universe is actually accelerating?  This was one of the biggest surprises in Cosmology back in 1998, leading to the discovery of the mysterious Dark Energy that makes up the vast majority of the energy density of the Universe.  Now to measure the expansion of the Universe, astronomers needed a way to accurately determine extreme distances.

One of the most effective ways to do this is to look at the apparent brightness of lights of a known magnitude.  Because light energy fades in a very predictable way (inverse square falloff), you can determine the distance accurately as long as you know the absolute brightness.  So try this thought experiment: if you went out on a deserted road at night and placed 100 watt light bulbs along the road every hundred meters, the closest lights would be the brightest and the farthest would be the dimmest - yet in reality they are all of the same absolute brightness.  If you stand next to each of them, they put out 100 watts of energy, but the light traveling from the farther ones loses energy, so it appears dimmer.  So by measuring the brightness of each light you could determine the distance because you know how bright it actually is and how bright it appears; essentially just by measuring the loss of energy over distance.

So how do we do this to measure the distance to stars?  As you can see in the image to the right, stars come in a wide variety of sizes and brightness (click to enlarge).  From the relatively cool, tiny Red Dwarf to the hottest, most massive blue Hypergiants, the brightness of stars varies considerably even amongst the same type.  With so much variation, it would be impossible to accurately use brightness to measure distance.  If only there was a class of bright object scattered throughout the Universe that always had the same brightness?  It turns out there is!

Read more…

One of my hobbies that’s a carry-over from my years as a soldier in the Army is long range shooting.  Understanding and exploiting the science of ballistics lets me take a particular load of ammunition and compute a predicted trajectory based on environmental factors such as barometric pressure, altitude and wind.  But there’s also an art form to creating a stable shooting platform with your body, controlling your breathing and making the shooting process fluid, not to mention estimating the wind speed and direction downrange.

Here’s a clip from a recent shoot out in the desert.  The targets are 10×17″ AR500 steel targets – about the size of a laptop screen.

Update:  I just came back from another trip out to the same area and this time made a few hits on the steel targets at a whopping 1750 yards.  Time of flight to the target was almost 2 seconds and it was another 3 seconds before we heard the report.

What the hell is that?  It looks like a comet, doesn’t it?  But it’s not.  Spectral analysis of the tail shows that it’s not gas and orbital analysis says it’s connected to the Flora family of near Earth asteroids.  What you’re looking at here is most likely a very recent asteroid impact with the debris trailing off, driven by the solar wind.  Initially the Lincoln Near-Earth Asteroid Research (LINEAR) sky survey discovered the unusual site and then Hubble was pointed at it to reveal the detail you see above.

This is pretty amazing and the very first time we have witnessed an asteroid collision!

Read more at the Hubble website…

So “Avatar” has been out for a few weeks now and I’m sure many of you have seen it.  If you haven’t, I highly suggest checking it out – especially in 3D.  Director James Cameron envisioned a lush world populated with rich texture and detail and used an army of visual effects artist to create it.  The story isn’t something new, but the experience of “Avatar” is.

There is however one key plot point that I’d like to talk about and a related evolutionary story, so if you haven’t seen the movie yet, you may want to wait to read this.

Potential spoilers below…

Read more…

Critical Thinking in many ways forms the backbone of Science because it uses logic and reason to come to conclusions devoid of emotional influences.  Personally I have a hard time seeing how people can see this as a problem because quite simply “it works”, yet I’m often dismayed by a substantial portion of the public specifically because they do not embrace Critical Thinking.  Perhaps this is because it (and Science for that matter) gets only cursory exposure in our basic education system, but I suspect the main culprit is parents and the way they raise their children.  Political and Religious ideologues completely ignore Critical Thinking, instead valuing what I like to call “Emotional Thinking.”  No doubt there’s a time and a place for emotions, but when it comes to understanding reality or seeking truth, emotions can be horribly unreliable.

The author of a previous video on Open Mindedness has posted a new video about Critical Thinking that’s an excellent primer on the concept and shows why it’s not only effective but something we should all strive to do.

Did you know that gravity is a bit of a mystery to scientists?  Given that we have space probes orbiting Saturn and Mars right now, you’d think it would be well understood, but the reality is it’s the most mysterious of the Four Fundamental Forces of Nature.   Mathematically it’s well understood and can be calculated with great precision, yet it’s so weak compared to the other forces, all of which are roughly comparable to each other.  How weak? Try – 10⁴⁰ weaker than the electromagnetic force, in other words:

0.00000000000000000000000000000000000000001 times as strong

Don’t believe me? Ever notice that you can pick up a paper clip with a refrigerator magnet, which is pretty weak, with relative ease?  The gravity from the entire mass of the Earth is being defeated by that little magnet, which seems so unintuitive and bizarre, doesn’t it?

The Four Fundamental Forces of Nature, according to the Standard Model, are Electromagnetism,  Strong Nuclear Force, Weak Nuclear Force and Gravity.  This isn’t speculation either – the Standard Model is one of the greatest achievements in Science, forming the backbone of modern physics and it works exceptionally well.

These forces interact with matter via carrier particles (aka bosons) and have a finite range to their interaction – except gravity.  To this day there is no known force carrier particle for gravity (they’ve been theoretically dubbed “gravitons”); it can’t be absorbed or shielded like the other forces; it has an unlimited range and it’s behavior is always attractive in nature; it’s somehow tied to the mass of objects in that it interacts with every particle that has mass.

Understanding gravity has been a long and storied endeavor, but it was Sir Issac Newton who made the first significant breakthrough when he published his Principa Mathematica in the 17th Century, wherein he described his universal law of gravitation.  His simple equation was highly accurate at calculating the motion of everything from objects falling out of a tree to the orbit of planets.  His work survived for two hundred years as the dominant theory of gravity until Einstein came along in 1905 and fundamentally changed the way we think of gravity.

Part of the problem was that there was no known mechanism for gravity.  It’s effects could be calculated, but it wasn’t clear how, for example, the Sun reach out to the Earth, across 93 million miles of empty space and tugged on it.  Einstein wondered if the Sun disappeared, how would the Earth know?  In other words, how did the force actually work to travel that distance?  Part of the problem it turns out was that we were thinking of Gravity in the same way we thought of the other known force at the time: electromagnetism.  Einstein radically overturned Newton by defining gravity not as a typical force but as curvature of space itself.  When Einstein published his Theory of Relativity ushered in a new age of physics, solving many of the outstanding problems of Newton’s theory – mainly that because gravity distorts space, the Sun reaches out to the Earth through that distortion to pull the Earth inward.

Einstein’s theory was confirmed  in many areas such as resolving the long standing anomaly with Mercury’s orbit that Newton’s theory couldn’t account for as well as the observed phenomenon of light being refracted by the mass of the Sun during a total eclipse.  Like any good theory, Einstein’s work makes lots of testable predictions that have been observed over the years, but around the same time he was getting lots of attention in the world, the world of atoms was slowly being revealed and it required a new kind of physics to describe.

Quantum Mechanics is to sub-atomic particles what General Relativity is to the orbit of planets.  It’s the physics that accurately models the way atoms and sub-atomic particles interact and has been tested to a high degree of accuracy as well.  There is a really big problem though: Quantum Mechanics does not jibe well with General Relativity.  Physicists tried using Einstein’s equations to model the interactions of molecules and atoms to find that as you get down to those very small scales, everything starts to fall apart and you get gravitational values of infinity (psst, that’s a sign there’s a problem with your theory).

So General Relativity is shown repeatedly to be correct on large scales and Quantum Mechanics is shown to be accurate the same way at the sub-atomic scale – what gives?  Gravity is messing things up in a big way or should I say our incomplete understanding of gravity is messing things up.  Finding an accurate quantum-scale model of gravity has been an elusive quest for physicists.  Some of the ongoing attempts include Loop Quantum Gravity*and String Theory, both of which are so theoretical that they currently can’t be tested in the first place.

This is why the Large Hadron Collider (LHC)  is particularly exciting to physicists.  It’s hoped that when it’s operating at full power, the LHC will be able to expose the innards of the sub-atomic world at an energy scale never before witnessed.  This could be the very device that detects gravitons, the theoretical force carrier for gravity or the Higgs boson which is theorized to give particles mass (remember, gravity is related to mass).  Exciting stuff!

So gravity remains a mystery for now; something we understand well enough to calculate its behavior extremely accurately, but mysterious enough that its mechanism remains elusive.

* Read Lee Smolin’s “Three Roads to Quantum Gravity” for an introduction to the theory…have aspirin handy.

One hundred fifty years ago today, Charles Darwin published one of the most important publications in all of Science – “On the Origin of Species.”  Darwin had been developing his scientific theory of evolution by natural selection for a number of years based on evidence gathered from around the world, particularly his excursion in the Galapagos Islands.  If his theory was correct, it would challenge the very fabric of our understanding of life on Earth, something that he wisely didn’t take too lightly in the 17th Century.

In the decades that followed, Darwin was attacked and ridiculed particularly by the Church of England, but in the scientific community he was supported and eventually lauded for his work.  But for the man himself, who was once firmly entrenched in a religious life, the results of his work led him to more secular beliefs which deeply conflicted with those of his wife.  It’s ironic that in many ways Darwin was exploring biology to help confirm his religious beliefs yet in the end the results he could not deny ended up pushing him to adopt agnosticism.

So as much as “On the Origin of Species” is a scientific triumph, a scientific theory that has become the foundation of modern Biology and been confirmed by many independent fields (genetics, for example), it is also seen as a key publication in the eyes of the atheists, agnostics and secular humanists.  They see it as the first major attempt to push back against theology in the post-Enlightenment era.

I think Richard Dawkins summed up the importance of Darwin’s book when he wrote, “Living organisms had existed on earth, without ever knowing why, for over 300,000 million years before the truth finally dawned on one of them. His name was Charles Darwin.”

Galaxy Zoo,  just kicked off a new project: mergers!  For those unfamiliar with Galaxy Zoo, it’s a project started a couple years ago that takes data from the robotic Sloan Digital Sky Survey and distributes it online.  Using an applet, users can look at a galaxy and use tools to identify its features and classify it.  For a detailed explanation of Galaxy Zoo, read The Story So Far.

Earlier this year the Galaxy Zoo team attempted to start a new project to identify supernovae, but it had a few hiccups and was put back in development.  However, today they rolled out a new project that allows us to help them identify and classify galactic mergers.  These are some of the most beautiful objects in the Universe, when two or more galaxies are drawn together and fling apart and then together as their constituents are ripped by tidal forces.  It looks violent, but there’s literally so much space between stars in a galaxy that few if any ever actually collide as a result.  What I find really cool about this new project is that the applet identifies a merger, then runs a series of quick 2D simulations of galactic mergers with different parameters.  We look at the results and see if any of these match the look of the actual galaxy.  If a match is found, then it helps explain the initial conditions that lead to the merger.

Neat stuff! Join in and help out!